Laundry dryers are household appliances built for drying clothes and comprise a drying chamber or drum into which the clothes to be dried are introduced. The drying chamber is rotatably supported within a cabinet and made to rotate by means of a driving motor, typically consisting of an electric motor connected to the drying chamber via a belt. Operation of the dryer is controlled by the user through a control panel, typically situated on the front or upper panels of the cabinet.
Generally, laundry drying machines may be divided in two categories according to the air circuit type implemented therein with the purpose of managing air flow of drying air (process air). Laundry machines of a first category are denoted as vented dryers. In operation, vented dryers draw air from the outside into the laundry machine, heat it and then blow the heated air through the laundry to be dried and finally exhaust back outside such air together with moisture absorbed from the laundry. Laundry drying machines of the second category are denoted as condensation dryers. Condensation dryers are provided with a closed drying air circuit (process air circuit) comprising a moisture condensing unit—or simply condensing unit—adapted to condense moisture dispersed in process air. Therefore, there is no exhaustion of moisturized air from the laundry machine during operation.
Condensation dryers may be further subdivided in two subtypes according to the device used for condensing moisture from process air. The condensation dryers of the first subtype are provided with an air-air heat exchanger, which cools and de-moisturizes the process air by taking and then exhausting air from/to outside the dryer, thereby using ambient air as coolant. Conversely, the condensation dryers of the second subtype are provided with a heat pump system which has a refrigerant fluid evaporator portion for cooling and de-moisturizing the process air.
In a condensation dryer, a drying air inlet path is connected to the drying chamber on one side thereof, and a drying air exhaust path, e.g. another duct, starts from the other side of the drying chamber, while a drying air fan draws air through the inlet path and forces it through the drying chamber, from which the air exits via the exhaust duct.
An electric motor is provided to turn the drum or laundry drying chamber, and generally also the drying air fan, and, in a condense-type laundry dryer, also the cooling air fan. It is also possible that separate electric motors are used. Fan(s) and drum need to rotate to very different rotational speeds. For this reason, in case of one electric motor, the fan or the fans are usually mounted on the motor main shaft while the drum is driven by a first belt wound around the outer surface of the cylindrical drum and on an auxiliary shaft mounted on the motor casing. Such auxiliary shaft is typically rotated by the main shaft through a transmission arrangement comprising a second belt wound around a pulley, which is mounted on the auxiliary shaft, and a cylindrically grooved portion of the main shaft.
The European patent application EP 2 752 518 A1 discloses a laundry dryer with a laundry drying chamber rotatably mounted in a cabinet.
In order to mount the transmission arrangement on the motor and to allow maintenance interventions, the machine basement requires to include an appropriate seat which is formed between the motor casing attachment and the area in which the main motor shaft enters the drying air fan casing. Such seat has typically a concavity oriented upwardly, so it is prone to collect a liquid thereon.
Water collected in the transmission arrangement seat may be sprayed into the surrounding due to the rotational movement of the motor shaft, causing possible contact of water with live parts. According to the International Standard IEC 60335-1: “Household and similar electrical appliances-Safety”, the term “live part” indicates a conductor or conductive part intended to be energized in normal use, including a neutral conductor but, by convention, not a PEN conductor, where a PEN conductor is a protective earthed neutral conductor combining the functions of both a protective conductor and a neutral conductor.
Contact of water with live parts can lead to malfunctioning of the dryer and damage of the dryer.